CVE-2026-63911: In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: reset runtime state when cloning SAs iptfs_clone_state() clones the...

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: reset runtime state when cloning SAs iptfs_clone_state() clones the IPTFS mode data with kmemdup(). This copies runtime objects which must not be shared with the original SA, including the embedded sk_buff_head, hrtimers, spinlock, and in-flight reassembly/reorder state. If xfrm_state_migrate() fails after clone_state() but before the later init_state() call has reinitialized those fields, the cloned state can be destroyed by xfrm_state_gc_task() with list and timer state copied from the original SA. With queued packets this lets the clone splice and free skbs owned by the original IPTFS queue, leading to use-after-free and double-free reports in iptfs_destroy_state() and skb release paths. Reinitialize the clone's runtime state before publishing it through x->mode_data. Because clone_state() now publishes a destroyable mode_data object before init_state(), take the mode callback module reference there. Avoid taking it again from __iptfs_init_state() for the same object.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.16%

5.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 0e4fbf013fa566f274ce9b4ce698c75b1f998c52, < 9327252e04626d4bb02ca8c0c108fbe8eabf0c5a; >= 0e4fbf013fa566f274ce9b4ce698c75b1f998c52, < dfb9f6cbfa9826655a49698cf90eb800fce2178e; >= 0e4fbf013fa566f274ce9b4ce698c75b1f998c52, < 7f83d174073234839aea176f265e517e0d50a1d2
Linux	Linux	6.14

References

Timeline

Published: Jul 19, 2026
Last Modified: Jul 27, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-63911?

In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: reset runtime state when cloning SAs iptfs_clone_state() clones the IPTFS mode data with kmemdup(). This copies runtime objects which must not be shared with the original SA, including the embedded sk_buff_head, hrtimers, spinlock, and in-flight reassembly/reorder state. If xfrm_state_migrate() fails after clone_state() but before the later init_state() call has reinitialized those fields, the cloned state can be destroyed by xfrm_state_gc_task() with list and timer state copied from the original SA. With queued packets this lets the clone splice and free skbs owned by the original IPTFS queue, leading to use-after-free and double-free reports in iptfs_destroy_state() and skb release paths. Reinitialize the clone's runtime state before publishing it through x->mode_data. Because clone_state() now publishes a destroyable mode_data object before init_state(), take the mode callback module reference there. Avoid taking it again from __iptfs_init_state() for the same object.

How severe is CVE-2026-63911?

CVE-2026-63911 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.

How do I fix CVE-2026-63911?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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